A particularly useful form of inkjet printer comprises a body of piezoelectric material with ink channels formed, for example, by disc cutting. Electrodes can be plated on the channel-facing surfaces of the piezoelectric material, enabling an electrical field to be applied to the piezoelectric “wall” defined between adjacent channels. With appropriate poling, this wall can be caused to move into or out of the selected ink channel, causing a pressure pulse which ejects an ink droplet through an appropriate channel nozzle. Such a construction is shown, for example, in EP-A-0 364 136.
It is a frequent requirement to provide a high density of such ink channels, with precise registration across a relatively large expanse of printhead, perhaps an entire page width. A construction that is useful to this end is disclosed in WO 98/52763. It involves the use of a flat base plate that supports the piezoelectric material as well as integrated circuits performing the necessary processing and control functions.
Such a construction has several advantages, particularly with regard to manufacture. The base plate acts as a “backbone” for the printhead, supporting the piezoelectric material and integrated circuits during manufacture. This support function is particularly important during the process of butting together multiple sheets of piezoelectric material to form a contiguous, pagewide array of ink channels. The relatively large size of the base plate also simplifies handling.
A problem remains of reliably and efficiently establishing electrical connection between the ink channel electrodes and the corresponding pins of the integrated circuits. If the base plate is of suitable material and suitably finished, conductive tracks can be deposited on it, these tracks connecting in known manner with the IC pins. There remains the difficulty of establishing connections to channel electrodes.